If this does not work then the Onkyo has a hardware failure in the power supply circuit and requires repairs. The average cost for this type of repair is in the $200 range, which in most cases is more cost effective to purchase another receiver in lieu of repairs. However if you would like to have the unit repaired, you can use the link below to locate a tech in your area:

www.stereorepair.com

If you need further assistance let me know. Please do not forget to click the 5 STAR RATING, at the top of the page for my efforts. It is my livelihood and you can follow up at any time if needed.

Keith, It wasn't merely a suggestion- it was all you can try on a user level to fix this. If the receiver is still not powering up beyond 3 seconds and then clicking off, it's a hardware issue as mentioned above.